Question

Consider the following chemical reaction.
2H2O(l)→2H2(g)+O2(g)

What mass of H2O is required to form 1.4 L of O2 at a temperature of 335 K and a pressure of 0.965 bar ?

Answer 1

PV = nRT

P = 0.965 bar = 0.952 atm

V = 1.4 L

n = ?

R = Gas constant

T = temperature = 335 K

0.952*1.4 = n*0.0821*335

1.33 = n * 27.5

n = 1.33 / 27.5 = 0.0484 mole

From the balanced equation we can say that

1 mole of O2 is produced by 2 mole of H2O so

0.0484 mole of O2 will be produced by

= 0.0484 mole of O2 *(2 mole of H2O / 1 mole of O2)

= 0.0968 mole of H2O

mass of 1 mole of H2O = 18.015 g

so mass of 0.0968 mole of H2O = 1.74 g

Therefore, the mass of H2O required would be 1.74 g